Favipiravir and/or Nitazoxanide: a Randomized, Double-blind, Placebo-controlled Trial of Early Antiviral Therapy in COVID-19 (FANTAZE)

Smith et al., NCT04918927, FANTAZE, NCT04918927, Mar 2023

120 patient favipiravir early treatment RCT with results not reported over 2 years after completion.

The protocol has been published1.

Potential risks of favipiravir include kidney injury2-4, liver injury3-5, and mutagenicity, carcinogenicity, teratogenicity, embryotoxicity, and the creation of dangerous variants6-12.

2 favipiravir RCTs have results missing long after expected13,14
The trials report total actual enrollment of 1,128 patients.

Important missing comments or errors? Let us know.

Study covers favipiravir and nitazoxanide.

1. trialsjournal.biomedcentral.com, trialsjournal.biomedcentral.com/articles/10.1186/s13063-022-06533-0.

2. Abdulaziz et al., Clinical Features and Prognosis of Acute Kidney Injury in Hospital-Admitted Patients with COVID-19 in Egypt: A Single-Center Experience, Mansoura Medical Journal, doi:10.58775/2735-3990.1433.edu.eg, doi.org.

3. Ülger et al., Experimental evaluation of favipiravir (T-705)-induced liver and kidney toxicity in rats, Food and Chemical Toxicology, doi:10.1016/j.fct.2025.115472.sciencedirect.com, doi.org.

4. El-Fetouh et al., Experimental Studies on Some Drugs Used in Covid-19 Treatment (Favipiravir and Dexamethasone) in Albino Rats, Journal of Advanced Veterinary Research, 13:10, www.advetresearch.com/index.php/AVR/article/view/1635advetresearch.com.

5. Almutairi et al., Liver Injury in Favipiravir-Treated COVID-19 Patients: Retrospective Single-Center Cohort Study, Tropical Medicine and Infectious Disease, doi:10.3390/tropicalmed8020129.mdpi.com, doi.org.

6. Zhirnov et al., Favipiravir: the hidden threat of mutagenic action, Journal of microbiology, epidemiology and immunobiology, doi:10.36233/0372-9311-114.elpub.ru, doi.org.

7. Waters et al., Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: the special case of molnupiravir, Environmental and Molecular Mutagenesis, doi:10.1002/em.22471.wiley.com, doi.org.

8. Hadj Hassine et al., Lethal Mutagenesis of RNA Viruses and Approved Drugs with Antiviral Mutagenic Activity, Viruses, doi:10.3390/v14040841.mdpi.com, doi.org.

9. Shum, C., An investigational study into the drug-associated mutational signature in SARS-CoV-2 viruses, The University of Hong Kong, PhD Thesis, hub.hku.hk/handle/10722/344396hku.hk.

10. Shiraki et al., Convenient screening of the reproductive toxicity of favipiravir and antiviral drugs in Caenorhabditis elegans, Heliyon, doi:10.1016/j.heliyon.2024.e35331.sciencedirect.com, doi.org.

11. Cenikli et al., Does Favipiravir interact with DNA? Design of electrochemical DNA nanobiosensor to investigate the interaction between DNA and Favipiravir used in the treatment of COVID-19, Talanta, doi:10.1016/j.talanta.2025.128084.sciencedirect.com, doi.org.

12. Mihaljevic et al., DNA damage in peripheral blood lymphocytes of severely ill COVID-19 patients in relation to inflammatory markers and parameters of hemostasis, Mutagenesis, doi:10.1093/mutage/geac011.oup.com, doi.org.

13. Smith et al., Favipiravir and/or Nitazoxanide: a Randomized, Double-blind, Placebo-controlled Trial of Early Antiviral Therapy in COVID-19 (FANTAZE), NCT04918927, clinicaltrials.gov/study/NCT04918927clinicaltrials.gov.

14. Kara et al., Efficacy and Safety of Hydroxychloroquine and Favipiravir in the Treatment of Mild to Moderate COVID-19, NCT04411433, clinicaltrials.gov/study/NCT04411433clinicaltrials.gov.

Smith et al., 21 Mar 2023, Double Blind Randomized Controlled Trial, Mexico, trial NCT04918927 (history) (FANTAZE). Contact: jorgeep@unam.mx.